GRADY, Ark. (AP)  The Latest on a disturbance at an Arkansas prison that left three inmates injured (all times local):

12:25 p.m.

An Arkansas official says three inmates who were injured in a disturbance at a state prison have returned to the facility after being treated at area hospitals.

Arkansas Department of Correction spokesman Solomon Graves says the three inmates who were hospitalized after Thursday night”s disturbance at the Cummins Unit in Grady had swelling to the face. The department said Friday that inmates in a single housing area within the prison broke windows and damaged surveillance equipment.

Graves says the disturbance lasted approximately two hours, and that the inmates involved were restricted to an area around the barracks. No officers were injured in the disturbance.

The incident was the latest in a series of recent disturbances at Arkansas” prisons that have prompted multiple investigations.

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7:59 a.m.

Arkansas officials say three inmates were injured in a “disturbance” at a state prison, the latest in a series of incidents that are now under investigation by Arkansas State Police.

Arkansas Department of Correction spokesman Solomon Graves says inmates broke windows and damaged surveillance equipment in a housing area Thursday night at the Cummins Unit in Grady, about 55 miles (90 kilometers) southeast of Little Rock.

Graves says correctional officers regained control of the situation, but that three inmates were injured and taken to hospitals. Graves says no employees were injured.

State police are already investigating more than two dozen cases of prison unrest this year, including one in which inmates who had taken keys and a Taser from guards held three correctional officers hostage for three hours.